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  • Bacterial community composition of stream biofilms in spatially variable-flow environments.

Bacterial community composition of stream biofilms in spatially variable-flow environments.

Applied and environmental microbiology (2009-09-22)
Katharina Besemer, Gabriel Singer, Iris Hödl, Tom J Battin
ABSTRACT

Streams are highly heterogeneous ecosystems, in terms of both geomorphology and hydrodynamics. While flow is recognized to shape the physical architecture of benthic biofilms, we do not yet understand what drives community assembly and biodiversity of benthic biofilms in the heterogeneous flow landscapes of streams. Within a metacommunity ecology framework, we experimented with streambed landscapes constructed from bedforms in large-scale flumes to illuminate the role of spatial flow heterogeneity in biofilm community composition and biodiversity in streams. Our results show that the spatial variation of hydrodynamics explained a remarkable percentage (up to 47%) of the variation in community composition along bedforms. This suggests species sorting as a model of metacommunity dynamics in stream biofilms, though natural biofilm communities will clearly not conform to a single model offered by metacommunity ecology. The spatial variation induced by the hydrodynamics along the bedforms resulted in a gradient of bacterial beta diversity, measured by a range of diversity and similarity indices, that increased with bedform height and hence with spatial flow heterogeneity at the flume level. Our results underscore the necessity to maintain small-scale physical heterogeneity for community composition and biodiversity of biofilms in stream ecosystems.

MATERIALS
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Brand
Product Description

Supelco
Sephadex® G-50, Medium
Sigma-Aldrich
Sephadex® G-50, BioReagent, for molecular biology, DNA grade, fine
Sigma-Aldrich
Sephadex® G-50, BioReagent, for molecular biology, DNA grade, medium
Sigma-Aldrich
Sephadex® G-50, Superfine
Sigma-Aldrich
Sephadex® G-50, Fine